Add olive oil to a large pan over medium-high heat. Add the ground beef, breaking it up as it cooks, until browned (about 5 minutes).
Add the carrots, bell pepper, and celery and stir occasionally. Cook until the veggies are softened (about 4 minutes). Add in the garlic and cook 1 additional minute.
Stir in the remaining ingredients, reduce heat to medium-low, cover, and let simmer for about 20 minutes, stirring occasionally. The veggies should be very soft and the sauce should have thickened.
Serve hot on buns & enjoy!